To evaluate the clinical and electrodiagnostic testing (EDX) in ulnar neuropathy at the elbow (UNE) and differences according to site (humeroulnar arcade, HUA, vs. retroepicondylar groove, REG) and injury physiopathology (axonal vs. demyelinating), through prospective multicenter case-control study.Cases and controls were matched by age and sex. UNE diagnosis was made on symptoms. Statistical analysis was performed using Mann-Whitney, Chi-square and ANOVA tests.144 cases and 144 controls were enrolled. Sensory loss in the fifth finger (U5) had the highest sensitivity (70.8%) compared to clinical findings. Motor conduction velocity across-elbow (MCV-AE) reached the highest sensitivity (84.7%) in localizing UNE recording from at least one of two hand muscles (first interosseous-FDI and abductor digit minimi-ADM). Abnormal sensory action potential amplitude from U5 occurred more frequently in axonal than in demyelinating forms. Differences between REG and HUA regarded conduction block (CB) and job type.Clinical findings have less usefulness than EDX in UNE diagnosis. MCV-AE recorded from both ADM and FDI increases diagnostic accuracy. Axonal forms have greater clinical and EDX severity than demyelinating forms, that are more frequent in REG. Manual workers prevailed in HUA. These findings may be helpful in prognostic and therapeutic approaches.